1. Field of the Invention
This invention relates to the integration of stimulus signalling protocol communication systems with message protocol communication systems.
2. Description of the prior art
Stimulus signalling protocols and message protocols are two methods for transferring information over a communications network. Stimulus signalling is typically used for connecting simple (dumb) terminals to a more powerful host. Message protocols are typically used to connect between such hosts. Equipment has typically been developed and manufactured for use with either stimulus signalling protocol systems or message protocol systems but not both. Both types of protocol have different advantages and disadvantages and previously, in order to exploit the advantages of both protocols, users have needed to install equipment for each type of protocol or employ the use of a protocol conversion device. Such protocol conversions are complex and time consuming to develop and maintain.
An example of a stimulus signalling protocol is P-Phone which is a proprietary protocol developed by Northern Telecom Limited. P-Phone is typically used in telecommunications networks and equipment has been developed for use in this type of system. P-Phone is used for Northern Telecom""s DMS support of Centrex services. Simple terminals, for example, xe2x80x9cbusiness handsetsxe2x80x9d have been developed for use in this type of system. The term xe2x80x9cbusiness handsetxe2x80x9d is used herein to refer to any type of terminal in a communications network which has a number of input devices such as keys and buttons. A business handset usually also has display capabilities but this is not essential. FIG. 1 shows an example of a business handset which has a display panel 100, telephone hand piece 101, a message waiting lamp 102, a number of function keys 103, and a number of indication lamps 104.
When a user makes an action using the business handset shown in FIG. 1, for example by pressing a button on the handset, a signal is sent from the terminal to a node in the communications network to which the terminal is connected. Whenever an individual keypress is made an individual transaction occurs between the terminal and a node to which it is connected. For example, when a telephone number is entered in order to make a telephone call to a third party (called party) the digits are sent one at a time in separate transactions. Each individual key press constitutes a transaction. This illustrates how, a stimulus signalling protocol (also referred to as a stimulus response protocol) is a method of sending messages in a communications network whereby individual digits or other items of information are sent individually.
As discussed above an alternative to a stimulus signalling protocol is a message protocol. In a message protocol, a collection of related signalling information is sent as a discrete unit. For example, a called party number is sent as a single message together with additional call set-up information, clearing information or other additional information. An example of a message protocol system is the ITU-T H.323 multimedia conferencing standard.
Systems conforming to the H.323 standard allow audio and video telephony calls to be provided and also allow cross-platform application interworking which may be between similar computer architectures such as desktop computers, or completely different implementations such as dedicated video phone.
One problem is that systems and equipment that have been developed for use in stimulus signalling protocol communications systems are not compatible with message protocol systems. Two separate sets of equipment are required in order to make use of both systems. For example, FIG. 2 shows a stimulus signalling protocol communications system according to the prior art.
A user at location 26 has access to a business handset 23 and a computer 24 on his desk. The business handset is connected to a stimulus signalling protocol communications system, in this case a public switched telephone network (PSTN) 21. The computer 24 is connected to the Internet 22. A second user at location 25 also has a computer 24 and a business handset 23 which are connected similarly. The first user may use his computer 24 to send messages to the second user over the Internet 22 using a message protocol system but the stimulus signalling protocol business handset 23 cannot be used to send information over the Internet 22. Also, each user has two items on his desktop. This means that purchase and installation costs are increased and space is used.
For a stimulus signalling protocol such as the P-Phone signalling model, it is necessary that an xe2x80x9calways upxe2x80x9d connection is available between the terminal and an exchange or host. An xe2x80x9calways upxe2x80x9d connection is permanently active so that the terminal and exchange or host are always able to send and receive information over the connection at all times. This requirement is a result of the way that stimulus signalling protocol systems work. Stimulus signalling protocols were originally developed to facilitate the introduction of relatively xe2x80x9cdumbxe2x80x9d terminal units such as business handsets. These units needed to be simple because the overhead of both host and terminal message processing were significant factors in runtime efficiency of the overall switch. This was achieved in stimulus signalling protocols such as P-Phone by maintaining a state mapping of the terminal in the exchange. This enables host initiated state transitions to be reflected at the terminal so that all transfers whether from host to terminal or terminal to host are always initiated from the host. This allows central processor unit (CPU) occupancy and message throttling to be implemented centrally and for the runtime efficiency of the overall exchange (switch) to be improved. Central processor unit occupancy involves determining how busy the central processor unit is and message throttling is a method whereby some traffic is diverted in the event that the central processor unit is busy. However, an xe2x80x9calways upxe2x80x9d channel is required (i.e. a channel that is always open and available for use). For example, consider the situation when a voice mail message is left at the host and a message waiting indicator needs to be illuminated on the terminal. If an xe2x80x9calways upxe2x80x9d channel from the host to the terminal is not present then the message waiting lamp is not lit and the event is missed.
As already mentioned, the H.323 multimedia conferencing standard is an example of a message protocol system. The H.323 standard is an umbrella recommendation from the International Telecommunications Union (ITU). It sets standards for multimedia communication over packet based networks, including the Internet, which may not provide a guaranteed Quality of Service. H.323 entities may provide real-time audio, video and/or data communications. Support for audio communications is mandatory, while data and video services are optional. By complying with H.323 requirements the aim is that multimedia products and applications produced by different manufacturers can interwork and allow users to communicate without concern for compatibility. For example, H.323 establishes standards for compression and decompression of audio and video data streams, ensuring that equipment from different manufacturers can be used to receive and decompress the same information. The standard also establishes a common call set-up and control protocols.
H.323 defines four major components for a network based communications system: terminals, gateways, gatekeepers and multipoint control units (MCUs). Terminals are the user end-points on the communications network that provide realtime two way communications. All H.323 terminals must support voice communications; video and data are optional. H.323 specifies the modes of operation required for different audio, video, and/or data terminals to work together.
An H.323 gateway is an element that provides a connection or interface from the H.323 network to a non-H.323 communications network such as a public switched telephone network (PSTN). The H.323 gateway is able to translate between transmission formats and between communications procedures as well as being able to perform call set-up and clearing.
H.323 supports data conferencing using the ITU""s T.120 standard. Data conferencing involves communication between two or more parties. T.120 addresses point-to-point and multipoint data conferences. An H.323 system can support data by incorporating T.120 capabilities into endpoints. Thus the specified standard for provision of end-to-end data channels within an H.323 connection is T.120. The T.120 specification provides for both defined data channel types such as Whiteboarding and text chat and ad-hoc channel content to allow proprietary application support.
It is an object of the present invention to provide an apparatus and method for integrating stimulus signalling protocol communication systems with message protocol communication systems which overcomes or at least mitigates one or more of the problems noted above.
According to a first aspect of the present invention there is provided a method of sending information between a message protocol compatible terminal in a message protocol communications network and a gateway to a stimulus signalling protocol communications network, comprising the steps of:
(i) establishing a first, deactivated two-way communications channel between the terminal and the gateway;
(ii) opening a second two-way communications channel between the gateway and the terminal, said second two-way communications channel being associated with said first, deactivated, two-way communications channel;
(iii) sending stimulus signalling protocol information over said second, two-way communications channel;
(iv) detecting when information is about to be sent via said first, deactivated, two-way communications channel, on the basis of information sent over the second two-way communications channel and, if information is about to be sent via said first, deactivated, two-way communications channel, activating said first two-way communications channel; and
(v) sending information over said activated first two-way communications channel.
A corresponding communications network is provided comprising a message protocol communications network connected via a gateway to a stimulus signalling protocol communications network, said gateway comprising:
(i) a processor arranged to establish a first, deactivated two-way communications channel between a message protocol compatible terminal in said message protocol communications network and said gateway;
(ii) a second processor arranged to open a second two-way communications channel between the gateway and the terminal, said second two-way communications channel being associated with said first, deactivated, two-way communications channel;
(iii) a transmitter arranged to send stimulus signalling protocol information over said second two-way communications channel;
(iv) a detector arranged to detect when information is about to be sent via said first, deactivated, two-way communications channel, on the basis of information sent over said second two-way communications channel;
(v) an activator arranged to activate said first deactivated two-way communications channel if information is about to be sent via said first deactivated two-way communications channel; and
(vi) a second transmitter arranged to send information over said activated first two-way communications channel.
A corresponding gateway is provided said gateway being adapted to provide an interface between a message protocol communications network and a stimulus signalling protocol communications network, comprising:
(i) a processor arranged to establish a first, deactivated two-way communications channel between said gateway and a message protocol compatible terminal in the message protocol communications network;
(ii) a second processor arranged to open a second two-way communications channel between said gateway and said terminal, said second two-way communications channel being associated with said first, deactivated, two-way communications channel;
(iii) a transmitter arranged to send stimulus signalling protocol information over said second, two-way communications channel;
(iv) a detector arranged to detect when information is about to be sent via said first, deactivated, two-way communications channel, on the basis of information sent over the second two-way communications channel;
(v) an activator arranged to activate said first, deactivated, two-way communications channel if information is about to be sent via said first, deactivated, two-way communications channel; and
(v) a second transmitter arranged to send information over said first, activated two-way communications channel.
A corresponding program stored on a computer readable medium is provided, said program being intended for use on a gateway between a message protocol communications network and a stimulus signalling protocol communications network, such that said gateway is able to:
(i) establish a first, deactivated, two-way communications channel between a message protocol compatible terminal in said message protocol communications network and said gateway;
(ii) open a second two-way communications channel between the gateway and the terminal, said second two-way communications channel being associated with said first, deactivated, two-way communications channel;
(iii) send stimulus signalling protocol information over said second, two-way communications channel;
(iv) detect when information is about to be sent via said first, deactivated, two-way communications channel, on the basis of information sent over said second, two-way communications channel;
(v) activate said first, deactivated, two-way communications channel if information is about to be sent via said first, deactivated, two-way communications channel; and
(vi) send information over said first, activated, two-way communications channel.
This provides the advantage that stimulus signalling protocol information can be sent over a message protocol communications network and it is not necessary to carry out protocol conversion in order to do this. For example, a business handset in a P-Phone system can be used to send stimulus signalling information via a gateway into a message protocol communications network such as the Internet. In this way voice information from a P-Phone business handset is sent over the Internet and is accessed by a terminal that is message protocol compatible. A stimulus signalling protocol is associated with a message protocol and also discrete stimulus transactions such as P-Phone functions are encapsulated within a uniform message stream.
Preferably information about said stimulus signalling protocol is provided t said terminal. This enables the terminal to be both message protocol and stimulus signalling protocol compatible. For example, an emulation of a business handset can be created on the terminal (for example a PC) and this enables the user to make calls from the emulated business handset over the Internet or other message protocol network. The user does not require a PC and a business handset and this saves costs, space, and maintenance. Calls can be made to and from the emulated business handsets over message protocol networks such as data communications networks.
Further benefits and advantages of the invention will become apparent from a consideration of the following detailed description given with reference to the accompanying drawings, which specify and show preferred embodiments of the invention.